Many types of crash detection system have been proposed previously, and many crash detection systems are complex and/or expensive. The present invention seeks to provide an improved crash detection system.
According to the present invention, there is provided a crash sensor arrangement for a motor vehicle, the crash sensor arrangement including a first set of sensors having a respective sensor on each side of the vehicle, each sensor being an accelerometer having a predetermined sensing axis. Each of the sensors being mounted on the vehicle close to the outer skin of the vehicle and at a first longitudinal position such that the sensing axis of each sensor makes a predetermined angle to the longitudinal axis of the vehicle, the predetermined angle being between 30° and 60°, or between −30° and −60°, the sensing axes being mirror symmetrical to each other relative to the longitudinal axis of the vehicle, so that at the first longitudinal position, the sensing axes of the two sensors extending in different directions.
Preferably, the predetermined angle from the vehicle longitudinal axis is between 40° and 50°, or −40° and −50°.
Advantageously, the predetermined angle is substantially 45°, or −45°. An advantage of this is that the angles are orthogonal providing a very high degree of sensitivity and a good response in an impact situation.
Conveniently, the sensing axes of the sensors are directed forwardly and outwardly of the vehicle.
Preferably, in one embodiment the sensing axes are directed rearwardly and outwardly of the vehicle.
Advantageously, the sensors are mounted on the vehicle adjacent the “B” posts or pillars of the vehicle.
Conveniently, the sensors are mounted on the vehicle adjacent the “C” posts of the vehicle.
Preferably, the vehicle having sensors in accordance with this invention is additionally provided with a second set of sensors comprising two further crash sensors, mounted on respective sides of the vehicle at a second longitudinal position spaced from the first longitudinal position. The longitudinal spacing between the sensors of the first set of sensors and the sensors of the second set of sensors provide an enhanced sensitivity and helps ensure that signals of a high quality are generated which can be processed so that an appropriate signal is generated when an impact occurs.
Advantageously, each further crash sensor of the second set of sensors may be a contact sensor.
Conveniently, each crash sensor of the second set of sensors is an accelerometer located close to the outer skin of the vehicle, the sensing axis of the sensors of the second set of sensors being mirror symmetrical to each other relative to the longitudinal axis, but also extending in directions which differ from the directions of the axis of the sensors of the first set of sensors. An arrangement of this type is provided two pairs of sensors, the first pair of sensors being located at one longitudinal position and the second pair of sensors being at a second longitudinal position spaced from the first longitudinal position. The sensing axis of each pair of sensors are mirror symmetrical about the longitudinal axis. The sensors of each pair have a different sensor axis, thus providing a sophisticated and responsive sensor system.
Preferably, the accelerometer of each sensor of the second set of sensors has a sensing axis which extends substantially perpendicularly to the longitudinal axis of the vehicle.
Advantageously, each sensor of the second set of sensors is mounted on the vehicle adjacent an “A” post of the vehicle, or in a door of the vehicle.
Conveniently, the vehicle is provided with at least one front sensor.
Preferably, the vehicle is provided with two front sensors.
In one embodiment, the one or more front sensors is a contact sensor.
Alternatively, the one or more front sensors is an accelerometer.
In one arrangement, the sensing axis of each accelerometer forming a front sensor is substantially aligned with the longitudinal axis of the vehicle.
In an alternative arrangement, the sensing axis of each accelerometer forming a front sensor is between 30° and 60°, or between −30° and −60° relative to the longitudinal axis of the vehicle, the axis of the front sensors being mirror symmetric relative to the longitudinal axis of the vehicle.
Advantageously, a central control unit is provided to receive signals from the sensors and to control the deployment or actuation of one or more safety devices within the vehicle.
Conveniently, all of the sensors are located close to the outer skin of the vehicle. An advantage of an arrangement of this type is that no central sensor is required. The sensors of the arrangement are all located close to the outer skin of the vehicle, but the combination of signals generated by the sensors is capable of providing a very reliable output.